Nashbar Deluxe Frame Adapter. Transporting kid's bikes, women's bikes, and bikes with steeply sloping top tubes can be a challenge if the design of your bicycle rack depends on the bike having a level top tube for optimal support. But that's where the Nashbar Deluxe Frame Adapter comes in and provides a solution. This sturdily built, easily adjustable frame adapter attaches to the seatpost and stem and serves as a level top tube for bike rack support purposes.